Anna University Solved Problems

ANNA UNIVERSITY SOLVED PROBLEMS

Problem 1.4

Lattice constant of a BCC crystal is 0.36 nm. Find its atomic radius.

Given data

a = 0.36 nm = 0.36 × 10-9 m

Solution

Problem 1.5

Copper is FCC whose atomic radius is 1.26 × 10-10 m. Calculate its lattice constant.

Given data

r = 1.26 × 10-10 m.

Solution

substituting the given value, we have

Problem 1.6

An element has a HCP structure. If the radius of the atom is 1.605 Å, find the volume of unit cell.

Given data

r = 1.605 Å = 1.605 × 10-10 m

Solution

In the case of HCP,

⸫ c = 5.24 × 10-10 m

Problem 1.7

Copper has a fcc structure and its atomic radius is 1.273 Å. Find (1) lattice parameter and (2) density of copper.

Atomic weight of copper = 63.5 

Avagadro's number = 6.02 × 1026 mol-1

Given data

Atomic radius for fcc system r = 1.273 Å

= 1.273 × 10-10 m

Atomic weight of copper M = 63.5

Avagadro's number N = 6.02 × 1026 mol-1

Number of atoms per unit cell n = 4

Solution

Problem 1.8

α-iron of atomic weight 55.85 solidifies into BCC structure and has a density 7860 kg m-3. Calculate the radius of an atom.

Given data

Atomic weight M = 55.85

Density ρ = 7860 kg m-3

Number of atoms per unit cell for BCC = 2

Avagadro's number N = 6.023 × 1026 mol-1

Solution

Substituting the given values, we have